Cannabinoid compounds are known to have a wide variety of biological effect on mammals, many of which are of potential therapeutical value, see R Mechoulam Ed., Cannabinoids as Therapeutic Agents CRS Press, Boca Baton, Fla. 1986. The drawback of many of the compounds which have such potential are side effects, and especially cannabimimetic effects which are highly undesirable.
According to the present invention the drawbacks have been overcome to a large extent, and the pharmaceutical compositions of the present invention are essentially devoid of such psychotropic side-effects. In R. Mechoulam et al, in The Cannabinoids: Chemical, Pharmacologic and Therapeutic Aspects, Academic Press, Ed. S. Agurell, W. L. Dewey and R. S. Willette, Orlando, Fla., 1984, pp 777-795, there have been published data on compounds which have a chirality which is opposite to that of the natural compounds, i.e. it is (3S,4S) rather than (3R,4R) of the natural compounds. An example of these compounds is the 1",2"-dimethyl heptyl homolog of (3S,4S)-(+)-.DELTA..sup.6 -THC.
This is a potentially valuable analgetic, however, it still causes some cannabimimetic side-effects, which may be due to the fact that the product may contain a minor quantity of the (3R,4R) enantiomer, which is strongly cannabimimetic.
As set out above, the present invention overcomes these drawbacks, and there is provided a synthetic route which makes possible to obtain the (3S,4S) enantiomers of the desired derivatives in essentially pure form, devoid of the undesired admixture of the (3R,4R) enantiomers.